For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition 65 WarningHorns
Specifications
Horn Replacement
Preliminary Procedure
Remove the front bumper fascia. Refer to Front Bumper Fascia Replacement.
Horn Nut
Caution: Refer to Fastener Caution in the Preface section.
Tighten
17 N·m (13 lb ft)
Horn
Tip
Disconnect electrical connectors.
St ...
SIR Inflator Module Handling and Storage Warning
Warning: When carrying an undeployed inflator module:
Do not carry the inflator module by the wires or connector.
Make sure the air bag opening points away from you.
When storing an undeployed inflator module:
Make sure the air bag opening points away from the surface on which
the in ...
Interior Trim and Paneling
Specifications
Front Side Door Window Switch Bezel Replacement
Preliminary Procedure
Remove the front side door trim. Refer to Front Side Door Trim Replacement.
Front Side Door Window Switch Bezel Screw (Qty: 8)
Caution: Refer to Fastener Caution in the Preface section.
Tighten
...